1. Field of the Invention
The field of the invention relates to jitter buffers, an in particular, to dynamically controlling jitter buffers in communication networks.
2. Description of the Prior Art
The transfer of real-time or time sensitive communications over packet networks has become very common. For example, voice and video over packet (VoP) services are currently very popular. Other examples of transferring real-time packet services include gaming and audio services provided over packet networks.
One drawback to transferring real-time communications over packet networks is that traffic degradation frequently occurs due to congestion and network failures. Several other factors that service providers and network operators must contend with to combat traffic degradation include latency, jitter, and packet loss. The effect on end users of traffic degradation is a poor quality experience. Oftentimes end users will talk over each other, such as in the case of a two-way voice conversation. Other times, users will experience silence. Traffic degradation can also impact the operation of network equipment and can result in prematurely dropped calls.
Jitter buffers are commonly used to reduce traffic degradation. In a typical example, real-time communication traffic is received into a jitter buffer at an uneven rate. The jitter buffer includes a memory buffer of a certain size that buffers the incoming traffic. The jitter buffer then plays out the traffic at an even pace, thereby smoothing the traffic.
The smoothness of traffic and the delay associated with the traffic are directly related. Traffic smoothing will improve as the size of a jitter buffer increases. However, delay will also increase as the size of a jitter buffer increases. As the size of a jitter buffer is reduced, the quality of the smoothing will also be reduced. However, the delay will also shrink. A jitter buffer that is too large will create an undesirable amount of delay in the buffered traffic. A jitter buffer that is too small will increase the amount of packet loss associated with the buffered traffic, as packets will be discarded from the jitter buffer to create space for more incoming traffic.
Dynamic jitter buffers have been introduced in the prior art to reduce delay and packet loss. The size of dynamic jitter buffers can be increased or decreased as required by traffic conditions. Unfortunately, most prior art solutions for dynamically controlling jitter buffers are overly complex and therefore expensive. In addition, many prior art solutions often times adjust jitter buffers too frequently. Other times, jitter buffers are not adjusted often enough.